RNA AND PROTEIN SYNTHESIS

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RNA AND PROTEIN SYNTHESIS
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How your cell makes very important proteins

• The production (synthesis) of proteins.
• 3 phases
• 1. Transcription
• 2. RNA processing
• 3. Translation
• DNA ? RNA ? Protein

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DNA ? RNA ? Protein

Eukaryotic Cell
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Before making proteins, Your cell must first make
RNA

• Question
• How does RNA (ribonucleic acid) differ from DNA
  (deoxyribonucleic acid)?

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RNA differs from DNA

• 1. RNA has a sugar ribose
• DNA has a sugar deoxyribose
• 2. RNA contains uracil (U)
• DNA has thymine (T)
• 3. RNA molecule is single-stranded
• DNA is double-stranded

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(No Transcript)
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1. Transcription

• Then moves along one of the DNA strands and links
  RNA nucleotides together.

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1. Transcription OR RNA production

• RNA molecules are produced by copying part of DNA
  into a complementary sequence of RNA
• This process is started and controlled by an
  enzyme called RNA polymerase.

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1. Transcription

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Question

• What would be the complementary RNA strand for
  the following DNA sequence?
• DNA 5-GCGTATG-3

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Types of RNA

• Three types of RNA
• A. messenger RNA (mRNA)
• B. transfer RNA (tRNA)
• C. ribosome RNA (rRNA)
• Remember all produced in the nucleus!

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mRNA

• Carries instructions from DNA to the rest of the
  ribosome.
• Tells the ribosome what kind of protein to make
• Acts like an email from the principal to the
  cafeteria lady.

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A. Messenger RNA (mRNA)
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If the cell is a school

• The Nucleus is the school office
• The Nucleolus is the principals office
• The DNA is the principal
• Ribosomes are the cafeteria ladies
• mRNA is the email from the principal to the
  cafeteria lady

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rRNA

• Part of the structure of a ribosome
• Helps in protein production

tRNA
A go-getter. Gets the right parts to make the
right protein according to mRNA instructions
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B. Transfer RNA (tRNA)

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2. RNA Processing

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2. RNA Processing

• Introns are pulled out and exons come together.
• End product is a mature RNA molecule that leaves
  the nucleus to the cytoplasm.
• Introns bad Exons good!

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2. RNA Processing

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Ribosomes
Large subunit

P Site
A Site
Small subunit
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3. Translation - making proteins

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3. Translation

• Three parts
• 1. initiation start codon (AUG)
• 2. elongation
• 3. termination stop codon (UAG)
• Lets make a PROTEIN!!!!.

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3. Translation
Large subunit

P Site
A Site
Small subunit
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Initiation

anticodon
A
U
G
C
U
A
C
U
U
C
G
A
hydrogen bonds
codon
mRNA
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Elongation
peptide bond
aa1
aa2

1-tRNA
2-tRNA
anticodon
U
A
C
G
A
U
A
U
G
C
U
A
C
U
U
C
G
A
hydrogen bonds
codon
mRNA
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aa1
peptide bond
aa2

1-tRNA
U
A
C
(leaves)
2-tRNA
G
A
U
A
U
G
C
U
A
C
U
U
C
G
A
mRNA
Ribosomes move over one codon
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peptide bonds
aa1
aa2
aa3
2-tRNA
3-tRNA
G
A
U
G
A
A
A
U
G
C
U
A
C
U
U
C
G
A
A
C
U
mRNA
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peptide bonds
aa1
aa2
aa3
2-tRNA
G
A
U
(leaves)
3-tRNA
G
A
A
A
U
G
C
U
A
C
U
U
C
G
A
A
C
U
mRNA
Ribosomes move over one codon
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peptide bonds
aa1
aa2
aa4
aa3
3-tRNA
4-tRNA
G
A
A
G
C
U
G
C
U
A
C
U
U
C
G
A
A
C
U
mRNA
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peptide bonds
aa1
aa2
aa3
aa4
3-tRNA
G
A
A
4-tRNA
G
C
U
G
C
U
A
C
U
U
C
G
A
A
C
U
mRNA
Ribosomes move over one codon
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aa5
aa4
Termination
aa199
aa200
primary structure of a protein
aa3
aa2
aa1
terminator or stop codon
200-tRNA
A
C
A
U
G
U
U
U
A
G
C
U
mRNA
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End Product

• The end products of protein synthesis is a
  primary structure of a protein.
• A sequence of amino acid bonded together by
  peptide bonds.

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Question

• The anticodon UAC belongs to a tRNA that
  recognizes and binds to a particular amino acid.
• What would be the DNA base code for this amino
  acid?

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Answer

• tRNA - UAC (anticodon)
• mRNA - AUG (codon)
• DNA - TAC